Automatic A/D converter operation with selectable result format

DETAILED DESCRIPTION What is claimed is: 1.
An analog-to-digital conversion system comprising: (a) an address bus; (b) an N-bit data bus; (c) an analog input terminal; (d) a sample and hold circuit having an input coupled to the analog input terminal and having an output; (e) an analog-to-digital converter circuit having an input coupled to the output of the sample and hold circuit and having an M-bit digital output, where M is less than N; (f) an interface circuit coupled to receive an address from the address bus and coupled to provide data to the data bus, the interface circuit also having an input coupled to the M-bit digital output of the analog-to-digital converter, the interface circuit further comprises: a data format circuit coupled to receive at least a portion of the address, the data format circuit couples an M-bit digital signal received from the analog-to-digital converter to either a first portion of the N-bit data bus or a second portion of the N-bit data bus, depending on a value of the portion of the address received by the data format circuit.
2.
An analog-to-digital conversion system according to claim 1 wherein the data format circuit further comprises: means for coupling the M-bit digital output to a least significant M bits of the N-bit data bus; and means for coupling the M-bit digital output to a most significant M bits of the N-bit data bus.
3.
An analog-to-digital conversion system according to claim 2 wherein the data format circuit further comprises: means for coupling the M-bit digital output to a most significant M bits of the N-bit data bus and for inverting a most significant bit of the M-bit digital output.
4.
An analog-to-digital conversion system according to claim 2 wherein the data format circuit further comprises: means for coupling the M-bit digital output to a least significant M bits of the N-bit data bus and for coupling a most significant bit of the M-bit digital output to each of the N minus M most significant bits of the N-bit data bus.
5.
An analog-to-digital conversion system according to claim 2 wherein the data format circuit further comprises: means for coupling the M-bit digital output to a least significant M bits of the N-bit data bus and for coupling a most significant bit of the M-bit digital output to a most significant bit of the N-bit data bus